Device and method for determining a spatial position of an object

ABSTRACT

In an arrangement and method for determining a spatial position of an object on a thermal basis, an imaging thermal sensor detects a thermal image of the environment and outputs corresponding signals to a processing unit coupled to the sensor. The processing unit accepts the signals, evaluates the image in view of a thermal marking, and determines the spatial position of the object dependent on the marking. The arrangement and the method can be employed in combination with a robot for orientation and for travel path control of the robot.

BACKGROUND OF THE INVENTION

The invention is directed to the determination of a spatial position ofan object.

The use of an autonomous robot system in industry is steadilyincreasing. The point of departure was the use of a robot system infabrication. This robot system was thereby utilized in stationaryfashion in order to implement repetitive but unchanging and permanentlyprescribed motion sequences. The demand for precision is thereby in theforeground. The disadvantage of this robot system is that it is bound toa location and, thus, has little flexibility.

T. Cord et al., Mobile autonome Roboter zum Transport von Containern,11. Fachgespräch, Karlsruhe, Eds. R. Dillmann, U. Rembold, T. Lüth,Springer Verlag, Berlin, Heidelberg, New York, pp. 1-9, 1995 discloses amobile robot system that is no longer stationary but can move by itself.The navigation of the movement is thereby accomplished with specificpreparations in the environment of the robot.

One example of this robot system is the driverless transport system thatis used for transporting materials. This system is usually track-guided,i.e. it follows a fixed path. This concept has proven itself in practicebut has the disadvantage that it is extremely inflexible—see DE 35 36974 A1. This is to be attributed thereto that the navigation control ofthe robot system ensues with a permanently present guide track Cord etal, supra. Before the transport robot is placed in operation, this ispermanently introduced into the floor in the form of an electricalconductor along the travel path. An involved re-laying of the conductoris required given a change of the path guidance. The old conductor mustbe removed from the floor, the floor covering must be repaired, the newpath guidance must be defined and the conductor must be placed into thefloor along the new path. This denotes a great time expenditure and highcosts.

R. Bauer, Integriertes hieracrhisches Navigationssystem für autonomemobile Roboter, pp. 17-23, pp. 35-41, Dissertation, Linz University,1997 discloses an autonomous mobile robot system that is in the positionof orienting itself, navigating and autonomously implementing apredetermined task in a dynamically changing environment completelyindependently without requiring a great expense for the preparation ofthe environment.

Various types of a position identification and navigation system havebeen developed therefor—Bauer. Such a system usually works on the basisof an imaging sensor. A sensor that detects the surroundings of therobot is thereby attached to the robot. Upon employment of a standardprogrammable computer, the sensor data are interpreted and a plot of theenvironment, similar to a map, is built up.

This map is interpreted in computer-supported fashion. Taking thekinematic and geometrical properties as well as the current position ofthe robot into consideration, the best possible navigation for apredetermined task is identified—DE 44 157 36 A1.

It is known from Bauer to employ an ultrasound sensor, a laser sensor ora stereo camera system as the sensor in a mobile robot.

The sensor system known from Bauer, however, exhibits a variety ofdisadvantages. Thus, the laser sensor or the stereo camera system is tooexpensive for the measurement use. In contrast thereto, the ultrasoundsensor in fact has a low price and great ruggedness. However, theprecision of such a sensor, its susceptibility to disturbance withrespect to a temperature fluctuation, an external signal or a multiplereflection and the low range of the sensor make the use thereof onlyconditionally possible.

R. Bruchhaus, D. Pitzer, R. Primig, M. Schreiter, W. Wersing, N.Neumann, N. Hess, J. Vollheim, R. Köhler, M. Simon, An 11×6 ElementPyroelectric Detector Array Utilizing Self-Polarized PZT Thin Film Grownby Sputtering, Integrated Ferroelectrics, Vol. 17, pp. 369-376, 1997also discloses that a pyroelectric material be employed for thedevelopment of a thermal sensor.

SUMMARY OF THE INVENTION

It is an object of the invention to determine the spatial position of anobject in a flexible and cost-beneficial way.

According to the arrangement of the invention for determining a spatialposition of the first object, an imaging thermal sensor is provided. Aprocessing unit coupled to the sensor is provided with which a spatialposition of the first object is identifiable from corresponding signalsof the sensor with reference to at least one thermal marking that isacquired by the sensor. In a method of the invention for determining aspatial position of the first object with an imaging thermal sensor anda processing unit coupled to the sensor, with the sensor detecting athermal image of the environment and outputting corresponding signals tothe processing unit. With the processing unit, accepting the signals,evaluating the image in view of at least one thermal marking, anddetermining a spatial position of the first object dependent on themarking.

The arrangement for determining a spatial position of a first objectcomprises an imaging thermal sensor and a processing unit coupled to thesensor. The processing unit is configured such that the spatial positionof the first object can be determined from corresponding signals of thesensor on the basis of at least one thermal marking that is acquired bythe thermal sensor.

An object whose temperature differs from an ambient temperature isemployed as thermal marking. The ambient temperature is the temperaturein the environment of the first object.

In the method for determining a spatial position of a first object withan imaging thermal sensor and a processing unit coupled to the sensor,the following steps are implemented:

a) the sensor detects a thermal image of the environment and outputscorresponding signals to the processing unit;

b) the processing unit picks up the signals, evaluates the image in viewof at least one thermal marking and determines the spatial position ofthe first object dependent on the marking.

The invention creates a very simple and cost-beneficial system forposition determination since low costs are incurred both for theproduction of the imaging thermal sensor as well as for the creation ofa thermal marking.

In particular, the possibility of being able to use a heat source thatalready exists, for instance a lighting member, or a thermal track thathas arisen in a natural way, for instance a damp cleaning track, as thethermal marking make the invention attractive and practical.

In addition to these advantages, the employment of a thermal marking hasthe advantage that it is usually not visible for a person and is thusnot disturbing.

The imaging thermal sensor is preferably a sensor with a pyroelectricthin-film. The sensor can thus be implemented as a very small andcost-beneficial component part.

It is provided in a further development that the arrangement comprises aunit that acts such on a second object such that the temperature of thesecond object differs from an ambient temperature and the second objectcan be recognized as the thermal marking. The advantage of thisembodiment is comprised therein that a system that can be very flexiblyutilized results due to the interaction of the first and second object.

The unit is preferably configured such that the second object ismoistened with fluid, as a result whereof the temperature of the secondobject differs from the ambient temperature. And the second object canbe recognized as the thermal marking. The advantage of this embodimentis comprised in the extremely simple and cost-beneficial way in whichthe thermal marking is produced.

Another advantageous development in view of the simplicity andcompactness of the arrangement derives when the unit that acts on thesubject object is the first object.

An especially simple structure of the arrangement derives when theimaging thermal sensor is attached to the first object.

The arrangement is preferably utilized such that the first object is arobot. In this way, there is a very simple, flexible and economicalsystem for position determination for the robot.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an orientation of a robot at a thermal track generated bythe robot itself;

FIG. 2 shows orientation of a cleaning robot;

FIG. 3 shows securing against a hazardous region with a thermal marking;and

FIG. 4 illustrates recognition of a human obstacle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

1. Orientation of a Robot at a Thermal Track Generated by the RobotItself

FIG. 1 shows the orientation of a robot 103 at a thermal track 104generated by the robot 103 itself.

By heating a sector 111 of a rear wheel 101 of the robot 103 with aheating element 102 worked into the rear wheel 101, the robot 103 heatselements at the floor 104 at predetermined intervals while travelling.Until they have completely cooled, these heated floor elements 104 acton the ambient temperature as thermal markings and form the thermaltrack 104.

The imaging thermal sensor 105 attached to the back side 112 of therobot 103 detects an ambient image 114 directed opposite the traveldirection 113 of the robot 103 at predetermined time intervals. Thesensor 105 is designed as described in Bruchaus et al.

Given straight-line travel of the robot 103, the sensor 105 supplies athermal ambient image 114 directed opposite the travel direction 113wherein the detected thermal markings 104 exhibit a very specific order.Deviations from the straight-line travel leads to changes in the thermalimage 114. The thermal image 114 is stored in a processing unit 106coupled to the sensor 105 that comprises a programmable processor 107and a memory 108 that are connected to one another via a bus 109. Theprocessor 107 reads the thermal image 114 from the memory 108 anddetermines the nature and extent of the deviation from the predeterminedtravel direction 113 from the modification of the thermal image 114.

The processor 107 determines a steering quantity therefrom that istransmitted to a steering unit 110 coupled to the processing unit 106.Dependent on the transmitted steering quantity, the steering unit 110positions the wheels 101, 115 of the robot such that the deviation fromthe straight-line travel is compensated.

2. Orientation of an Autonomous Cleaning Robot

FIG. 2 shows the orientation of the robot, which is utilized as cleaningrobot 201, at a fluid track 202 produced by the robot 201 itself.

Due to the dissipated evaporation energy of the fluid, damp floorelements 202 cool off compared to the ambient temperature and form athermal track 202. For orientation of the cleaning robot 201, this isutilized for two steering tasks:

The cleaning robot 201 employs the self-generated thermal track 202, asshown in exemplary embodiment 1, for controlling the straight-linetravel 206.

For an efficient cleaning of a surface 203 that is covered by adjoiningcleaning paths 204 a-d that proceed parallel to one another and arelaterally offset by the width of the cleaning robot 201 and traversed bythe cleaning robot 201 in alternating travel direction 207, the cleaningrobot 201 orients the cleaning path 204 b being currently traversed byit with reference to the thermal track 202 that was generated whiletravelling on the previously traversed cleaning path 204 a.

The arrangement of the thermal sensor 105, the structure and thefunctioning of the processing unit 106 is shown in exemplary embodiment1.

3. Segregation from a Hazardozus Region with a Thermal Marking

Another exemplary embodiment is shown in FIG. 3 and is explained ingreater detail below.

FIG. 3 shows an embodiment of the invention wherein the thermal sensoris employed in order to prevent the penetration of the robot 301 into aspatial region 302 a,b demarcated with a thermal marking 303. This isnecessary when a region 302 a,b of the room 302 accessible to the robotcomprises a risk potential. Such a region 302 a,b is the zone in theenvironment of an opening door 302 a or a stair step 302 b;

For this purpose, a resistance wire 303 is let into the floor thatlimits the region 302 a,b dangerous to the robot 301 at a prescribablesafety distance. The resistance wire heats the adjacent floor elements304 to a predetermined temperature and generates the thermal marking304.

A thermal sensor 306 that supplies the thermal ambient image in 312 atravel direction 313 and opposite the 312 b travel direction 313 of therobot 301 is attached to the front side 305 a and to the back side 305 bof the robot. The sensor 306 that is employed is designed as disclosedin Bruchhaus.

Due to the predetermined temperature, the thermal marking 304 expressesitself in this thermal image 312 a,b in a way that can be unambiguouslyrecognized by a processing unit 307.

The thermal image 31 2a,b is stored in a processing unit 307 coupled tothe sensor 306, said processing unit 307 comprising a programmableprocessor 308 and a memory 309 that are connected to one another via abus 310. The processor 308 reads the thermal image 312 a,b from thememory 309 and, based on the orientation of the thermal marking 304 inthe thermal image 312 a,b, determines the position of the robot 301relative to the thermal marking 304.

Dependent on the identified position, the processor 308 calculates asteering quantity that is transmitted to a steering unit 311 coupled tothe processing unit 307. The steering unit 311 positions the wheels 314of the robot 301 such dependent on the transmitted steering quantitysuch that the robot does not travel across the thermal marking 304.

4. Recognizing a Human Obstacle

Another exemplary embodiment is shown in FIG. 4 and is explained ingreater detail below.

When a mobile robot 401 is placed in a room 402 that is accessible to aperson 403, then the person 403 located in this room represents anobstacle for the robot 401. Due, however, to the natural body heat, theperson 403 is recognized as a human-specific thermal marking.

A thermal sensor 405 that supplies the thermal ambient image in 412 atravel direction 413 and opposite 412 b the travel direction 413 of therobot 401 is attached to the front side 405 a and to the back side 405 bof the robot. The sensor 405 that is employed is designed as disclosedin Bruchhaus.

Due to the body heat, the human-specific thermal marking 403 expressesitself in this thermal image 412 a,b in a way that can be unambiguouslyrecognized by a processing unit 406.

The thermal image 412 a,b is stored in a processing unit 406 coupled tothe sensor 405, said processing unit 406 comprising a programmableprocessor 407 and a memory 408 that are connected to one another via abus 409. The processor 407 reads the thermal image 412 a,b from thememory 408 and, based on the orientation of the thermal marking 404 inthe thermal image 412 a,b, determines the position of the robot 401relative to the thermal marking 403.

Dependent on the identified position, the processor 407 calculates asteering quantity that is transmitted to a steering unit 410 coupled tothe processing unit 406. The steering unit 410 positions the wheels 414of the robot 401 dependent on the transmitted steering quantity suchthat the robot travels around the thermal marking 403 at a predeterminedsafety distance.

A few modifications of the above-described exemplary embodiment areexplained below.

In order to prevent a collision between the robot 401 and the person403, the steering unit 410, dependent on the identified position of therobot 401, can stop the travel by shutting off the robot 401.

It is also provided to attach a warning device 411 to the robot 401 thatsupplies an audio-visual alarm signal dependent on the identifiedposition of the robot 401.

Although various minor changes and modifications might be proposed bythose skilled in the art, it will be understood that my wish is toinclude within the claims of the patent warranted hereon all suchchanges and modifications as reasonably come within my contribution tothe art.

I claim:
 1. An arrangement for determining a spatial position of a firstobject, comprising: an imaging thermal sensor which provides signalsindicative of a thermal image of an environment where the first objectis located; a thermal marking device which thermally marks one or moreregions of said environment; and a processing unit coupled to the sensorwhich generates said thermal image of the environment, which detects thethermal marking in said environment, and which determines said spatialposition of said first object based on the detected thermal marking inthe thermal image of the environment.
 2. The arrangement according toclaim 1 wherein the processing unit is configured such that the spatialposition of the first object is identifiable from imaging signals of thesensor on the basis of a plurality of thermal markings that are acquiredby the sensor.
 3. The arrangement according to claim 1, whereby theimaging thermal sensor is a sensor with a pyroelectric thin film.
 4. Thearrangement according to claim 1 further comprising a unit that acts ona second object such that the temperature of the second object isdifferent compared to the ambient temperature and the second object isrecognizable as a thermal marking.
 5. The arrangement according to claim4 whereby the unit is configured such that the second object ismoistened with fluid, so that the temperature of the second object isdifferent compared to the ambient temperature and the second object isrecognizable as a thermal marking.
 6. The arrangement according to claim4 wherein the unit that acts on the second object is the first object.7. The arrangement according to claim 1 wherein the imaging thermalsensor is attached to the first object.
 8. The arrangement according toclaim 1 wherein the first object is a robot.
 9. A method for determininga spatial position of a first object with an imaging thermal sensor anda processing unit coupled to the sensor, comprising the steps of:thermally marking one or more regions of an environment in which thefirst object is located; with the sensor detecting a thermal image ofsaid environment and outputting corresponding signals to the processingunit; also with said sensor detecting said thermal marking in saidenvironment; and with the processing unit, based on the signals from thesensor generating a thermal image of the environment and interpretingthat thermal image to detect the thermal marking in the thermal image,and determining said spatial position of said first object in theenvironment based on the detected thermal marking in the thermal image.10. The method according to claim 9 wherein the image is evaluated inview of a plurality of thermal markings and the spatial position of thefirst object is determined dependent on the thermal markings.
 11. Themethod according to claim 9 whereby a temperature of a second object ismodified such that the second object is recognized as a thermal marking.12. The method according to claim 11 whereby the second object ismoistened with fluid such that the temperature of the second object isdifferent compared to ambient temperature and the second object is thusrecognized as a thermal marking.
 13. The method according to claim 9whereby the processing unit determines a relative position of the firstobject with respect to the thermal marking from signals of the sensor.14. The method according to claim 9 wherein the processing unitdetermines an absolute position of the first object from signals of thesensor.
 15. A method for determining a spatial position of a firstobject with an imaging thermal sensor and a processing unit coupled tothe sensor, comprising the steps of: thermally marking a plurality ofregions of an environment in which the first object is located; with thesensor detecting a thermal image of said environment and outputtingcorresponding signals to the processing unit; also with said sensordetecting said thermal marking in said environment; and with theprocessing unit, based on the signals from the sensor generating athermal image of the environment and interpreting that thermal image todetect the thermal marking in the thermal image, and determining saidspatial position of said first object in the environment based on thedetected thermal marking in the thermal image.